Mesothelioma treatment has come a long way over the years, with new and innovative therapies entering clinical trials almost daily. Among the most promising treatments is targeted therapy, which works different from standard chemotherapy (chemo). Per the American Cancer Society, standard chemo drugs work by “killing cells in the body that grow and divide quickly.” Cancer cells divide quickly, “which is why these drugs often work against them.” But chemo drugs can also affect other cells in the body that divide quickly (healthy cells), which can sometimes lead to serious side effects such as long-term damage to cells in the heart, bladder, kidneys, lungs, and nervous system or delayed effects, such as a second cancer that may show up many years later.

Targeted therapy drugs, on the other hand, “target certain parts of cancer cells that make them different from other cells or they may target other cells that help cancer cells grow,” says the American Cancer Society. This causes fewer side effects and less damage to healthy cells. Targeted drugs can work to:

Block or turn off chemical signals that tell the cancer cell to grow and divide

Carry toxins to the cancer cells to kill them, but not normal cells

Change proteins within the cancer cells so the cells die

Stop making new blood vessels to feed the cancer cells

Trigger your immune system to kill the cancer cells

Though targeted therapy sounds promising, its effectiveness is still being studied, so experts say chemotherapy still remains one of the most valuable therapies to treat mesothelioma and other cancers. In fact, in many cases patients are given chemotherapy at the same time as targeted therapies to ensure that they are still being treated with a therapy that is known to be effective. Simply put, “chemo is often paired with still-unproven treatments to improve their odds of success,” said Dr. Robert Comis (a professor and oncologist at Drexel University) during an NPR Morning Edition program.

Experts say that not only do specialists rely on chemotherapy because it kills malignant cells, they also value the treatment because it has the proven ability to directly affect the immune system, making the body more resistant to new cells as they recur. Per NPR, “certain chemotherapy drugs can kill a type of T-cell that makes cancers more resistant to treatment. It also appears that after chemotherapy kills cancer cells, the debris that's left can sometimes stimulate an immune reaction. That leftover material is like a vaccine, in that it trains the immune system to recognize and attack remaining cancer cells.”

According to Dr. Leisha Emens, an oncologist at Johns Hopkins Bloomberg-Kimmel Institute in Baltimore, chemotherapy’s ability to directly affect the immune system is one of the most underappreciated roles of this mainstay treatment. In her clinical trials, Emens routinely gives standard chemotherapy along with the experimental treatment to enhance the effectiveness of treatment.

In the end, experts agree that though they are seeing more targeted agents becoming the standard that people expect to receive, “this is hardly the end of the road for traditional chemo,” says Dr. Elad Sharon of the National Cancer Institute (NCI). "I think there are some diseases where chemotherapy has really been very effective, and has led to significant cures," he says. “It's probably going to be very hard for any targeted agents to beat them."

Comis agrees. "We're in a transition state right now where the types of available treatments are changing," he says. "But we can't lose sight of the fact that cytotoxic chemotherapy has cured many, many patients." And using them in combination can make “these old standby drugs more effective.”

Per NPR, “in an ideal world highly toxic chemo would give way altogether to gentler and more effective medicines.” However, Comis “doesn’t see that day coming soon.”